1. Field of the Invention
This invention relates to the shaping of heat softenable material sheets and, in particular, to an adjustable roll forming arrangement for shaping hot glass sheets of varying transverse and longitudinal configurations.
2A. Technical Considerations
In the manufacture of tempered shaped glass sheets, glass sheets are normally heated to their heat softening temperature, shaped by one of a variety of well known forming operations and cooled to impart at least a partial temper in the glass sheet. In particular, in a roll forming operation the glass sheet is deformed by gravity to assume a transverse and/or longitudinal configuration. The transverse curvature is formed by conveying the hot glass sheet over a series of transversely curved longitudinally spaced forming rolls at the exit end of a heating furnace. The longitudinal curvature is formed by mounting the individual forming rolls along a longitudinally extending arc.
Current automotive design requires a variety of different glass sheet shapes and curvatures. Generally, a roll forming apparatus includes transversely curved conveyor rolls with rigid shafts that are mounted on a rigid support along a fixed longitudinal sweep so that the apparatus is limited to shaping glass to a single transverse and longitudinal radius curvature. It would advantageous to have an adjustable roll forming arrangement wherein both the transverse roll profile and the longitudinal profile of the roll forming apparatus can be easily adjusted to correspond to the transverse and longitudinal radius of different curved glass sheet configurations.
2B. Patents of Interest
U.S. Pat. Nos. 1,530,499 to Knode; 2,820,541 to Barnish et al.; 3,088,580 to Hughes; 3,089,580 to Dilgard and 3,092,240 to Tyler et al., each disclose an adjustable conveyor roll. In particular, Knode teaches a three part conveyor roll wherein the outer two sections of the roll may be pivoted upward relative to the horizontal center section. The remaining patents each teach a continuously curved conveyor roll wherein the transverse radius of curvature of the rolls can be varied. In each patent, the roll assembly is suspended at its opposite ends by pivoting support arms and the radius of curvature of the rolls is adjusted by pivoting the support arms so as to move the opposite ends of the conveyor rolls closer or further apart. In each of these patents the conveyor rolls are free wheeling i.e., they freely rotate about a central shaft and do not include a drive assemble to directly rotate the conveyor roll.
U.S. Pat. No. 3,881,906 to Ritter et al teaches a roll forming apparatus with a transition section between the heating furnace and shaping station. The forming rolls in the transition section have successively decreasing transverse radii of curvature, changing from a flat roll at the upstream end of the transition section to a forming roll with a configuration similar to those in the shaping station.
U.S. Pat. No. 4,311,509 to Reader et al., discloses a conveyor roll comprised of a rigid curved shaft and plurality of cylindrically shaped glass sheet support members mounted around the curved shaft. Each support member includes a hub having a loosely fitting tongue and groove connecting arrangement and an outer collar of material that does not mar a hot glass sheet when in contact therewith. The tongue and groove arrangement interconnect the support members so that when torque is applied to one end of the hubs of the conveyor roll, the glass engaging surface of the collars rotate in unison, preferable at a uniform speed, to convey the curved glass sheet. Each roll is supported within the quench section of a roll forming apparatus on a rigid frame.
U.S. Pat. No. 4,226,608 to McKelvey discloses flexible shaping rolls comprised of relatively tightly wound coil springs mounted on pivoting end supports by stub shafts. The transverse radius of curvature of the rolls is adjusted by positively pivoting the upper portion of the end supports in order to move bearing housings, which support the stub shafts, inwardly or outwardly, and simultaneously varying the angularity thereof. Each roll is mounted at the same elevation within a roll forming operation on a rigid frame.
U.S. Pat. Nos. 4,139,359 to Johnson et al., and 4,556,406 to Kahle teach roll forming operations wherein transversely extending curved conveyor rolls are longitudinally spaced along a longitudinally extending arc in order to impart a longitudinal curvature in the shaped glass sheet. In particular, Kahle teaches the positioning of the ends of each curved roll along a different longitudinally extending arc so as to shape a heat softened glass sheet into a configuration having a longitudinal radius of curvature that varies in a direction transverse to the glass sheet.
U.S. Pat. No. 4,619,683 to Halberschmidt et al. teaches an adjustable glass sheet blowing assembly for tempering glass sheets. Flexible tubular nozzle arrangements are secured to deformable rails that have an adjustable center support. The center support is adjusted to change the curved configuration along which the nozzle arrangement is mounted. Additional deformable rails may be used to flex the nozzle arrangement in their transverse direction.